1. Field of the Invention
This invention relates to arc length control of welding systems and, more particularly to computerized arc length control for processing arc weld current parameters and non-linear voltage-ampere characteristics to maintain the desired arc length.
2. Description of the Related Art
Control of arc length in commercial automatic welding systems is typically accomplished by a motorized servo system with arc length proportional to arc voltage. Arc length is maintained constant by a motorized weld torch driven from a differential output derived from comparing the arc voltage to a standard voltage. However, this methodology is problematic because the voltage characteristics for a constant arc length during a changing current is a non-linear function. Therefore, in a motorized system the desired arc length is not maintained during arc current variations. Generally, for maintaining a constant arc length, the arc current has been maintained constant. As will be disclosed below, the present invention provides maintenance of the constant arc length with variable arc current.